Baking cakes / the butterfly wing guy

Picasso said about the average artist: "they've made their mold – they just go off and bake their little cakes in that same mold." I try not to do this - I try to repeat myself as little as possible and always move forward.
A book a read through recently advises against my strategy. Taking the Leap talks about an artist who liked to paint butterfly wings. He was becoming well known for this, to the point where people began saying - "Hey - I know you - you're the Butterly Wing guy!" The artist resented this, and moved on to painting other subjects. The author of Taking the Leap scolds the artist for "sabotaging" his career. She says that the artist should have embraced the "pigeonholing", and points to successes such as Warhol ("The Soup Can guy").
An article I read on about.com also recommends the repeat-yourself strategy. It says:

Decide on a style, subject matter, palette, and value range that you love, and are comfortable doing. Narrow it down. Dogs? Too broad. One breed only. Too broad. One specific dog only. ... Do that one dog over and over, in the same narrow range of colors. ... . Case in point -- Cajun artist George Rodrigue with his famous Blue Dog.